Fashion's nonconformist queen, Dame Vivienne Westwood, is to hold back on business expansion to reconcile her fashion empire with her strong ecological beliefs and her concerns about mass production. She will concentrate instead on producing "quality not quantity" and continue to use her high-profile brand to put forward her political beliefs.

Launching a photo-campaign to promote Greenpeace's efforts to Save the Arctic, backed by George Clooney and singers Chris Martin and Paloma Faith, the designer said she wanted to concentrate on preserving and improving what her company already does, despite recent success in China and the US.

"I have decided not to expand any more. In fact I want to do the opposite," she told the Observer. "I am now more interested in quality rather than quantity."

Westwood, 72, said she did not want to defend the fashion industry, although she regards "true fashion" as an important part of culture. "Do I feel guilty about all the consumption that the fashion world promotes? Well, I can answer that by saying that I am now trying to make my own business more efficient and self-sustaining. This also means trying to make everybody who works in it happy, if I can."

Westwood's company made a £5m profit in 2012. The results were significantly up on the previous year, largely due to new shops, but the firm was criticised for unpaid work-experience schemes.

The designer from Derbyshire, who was born in Derbyshire andwho came to fame during the punk era for her partnership with the late music impresario Malcolm McLaren, said she regards it as possible to walk a line between high-end fashion and political activism.

"What I want people to be able to do is to buy well, by first choosing well and then making it last. And I also believe that if everyone wore just a few beautiful things, there would not be such a climate change problem," she said. "In my view it is worse for someone to come out of a shop with an armful of new T-shirts made in a sweatshop, than it is for a rich lady to buy one beautiful dress."

Westwood said that communicating the threat of climate change had become her priority and so she is keen to promote Greenpeace's work to protect the Arctic. "The status quo will kill us. People don't realise how quickly we are marching towards a possible mass extinction. Once the global temperature goes up beyond two degrees, you can't stop it. Current predictions are that we will see a rise of more like 4C or 6C, which would mean that everything below Paris would become uninhabitable."

In recent years Westwood's campaigning has focused on reforming business policy, the ecology of climate change, anti-fracking events, and supporting the charity Cool Earth's efforts to preserve the rainforests. The designer aims, she said, to work on areas with achievable goals and she chronicles her activities on the website Climate Revolution. She sees the western economy as "intertwined" with ecological danger, "like two snakes".

"I can't speak for the views of other fashion designers. Some of them don't seem to be interested in anything but fashion and they even go on holiday with designers and magazine editors, but they have all been very supportive of me."

Fashion shows for Westwood have also become an opportunity to talk about her beliefs. "Nobody has got cross with me, as far as I know, and said: 'Here she comes again!'"

The portraits for Greenpeace feature Clooney, Martin, Monty Python's Terry Jones and Terry Gilliam, as well as the modelling mother and daughter Jerry Hall and Georgia May Jagger and the actress Saffron Burrows, and they were taken by award-winning celebrity photographer Andy Gotts MBE.

"People want to support Vivienne Westwood," said Gotts. "She's so passionate. They see Vivienne as someone really special and people feel the urge to fight in her corner."

Westwood met Gotts at a charity photo shoot for Elton John and he offered to help with her campaign portraits. "Andy is popular with celebrities because he makes it all a pleasant experience. I also really relied on the help of Jerry Hall and Georgia May to do this," said Westwood. The T-shirt design, a heart-shaped globe, was picked for its clarity.

Celebrities are often the key to getting a message across, said Westwood, adding that she hopes to do more work with famous names. "Public opinion is very responsive to celebrity. The first thing I tend to do is ask them for a small amount of money, something that means nothing to them. Then they feel involved, rather than as if they are just doing me a favour."